The subject invention relates to industrial controls. It finds particular application in conjunction with combining block and modular I/O, integrating standard and safety messages and bridging of such safety signals in an integrated control network, and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications.
Machine control employs digital and/or analog communication to exchange information across various networks. Typically, various protocols are employed with such networks to facilitate communication between a controller(s) and one or more control components such as I/O modules, drives, servos, switches, sensors, etc. Conventional protocols accept data from a source (e.g., controller) and package the data for transmission to one or more data recipients (e.g., control components). In addition, such protocols have limited communication and typically are suitable only for certain layers within an automation pyramid and/or limited in their functionality (e.g., single master system running a master/slave protocol). This may result in barriers within the automation architecture that are difficult to penetrate and that require complex bridging devices without being able to fully bridge the gap between the various systems that are quite different in nature.
Machine control typically includes various safety devices and associated controls that can be used to mitigate machine accidents that can harm an individual. Conventional systems typically hardwire pushbuttons (e.g., an e-stop) directly into a controller to handle emergency situations which could result in harm to an individual. In this manner, a user can shut down an operation by pressing the appropriate button. Safety signals can also be sent through various communication channels within a control system to prevent a potentially dangerous condition from occurring. Such automated intelligence relies on particular signal levels (values) in order to initiate such a related safety change. Thus, maintaining the integrity of such safety signals is critical to insure that appropriate measures are taken in the event of an emergency. In one conventional technique, safety and non-safety data are kept separate, for example, within different networks.
A typical safety network is designed to detect errors and react with pre-determined safe operation. Typically, this means placing the output signals in a state which would cause the machine to stop. The protocol within a safety network takes measures to ensure a high level of integrity within the application. These measures, such as message redundancy and cross-checking, ensure that safety messages are reliably transmitted from one device and received at another in a predetermined time and with the integrity of the data content maintained or that the system goes to a predetermined safety state.
What is needed are systems and methods that permit flexible machine control architecture to transfer safety and non-safety data. Such flexibility includes the ability to transfer safety and non-safety data across multiple protocols within a single control architecture.